This invention relates generally to testing equipment for a telecommunications switch, and more particularly to a call processing monitor system which generates and analyzes the functions of a telephone call for determining if the switch is operating properly.
Testing the operability of telecommunications switches is necessary and is a common practice in the industry. If all the functions of a switch are not analyzed, especially before the switch is installed in the telecommunications network, an inherent problem in the hardware or software of the switch can go unrecognized until it fails in actual use. As a result, many telephone susbscribers could be unnecessarily out-of-service for an extended period of time. This problem can be resolved by troubleshooting or testing the hardware and software of the switch itself during its installation in the telecommunications switching network or during its repair period.
There are basically two types of telecommunication switches available--analog and digital. Analog switches have been around a long time and are characterized as having the same path connected through it for the voice channels of the originating and terminating lines of a telephone call. On the other hand, digital switches have recently came about with the advent of the computer age and are characterized by using state-of-the-art techniques to enhance their efficiency and reduce their size. Typically, the voice channels for the originating and terminating lines of a telephone call through this type of switch follow different paths. This is because digital switches employ multiplexers and other high technology telecommunication transmission devices to allow many different voice channels to be carried over a single transmission line.
Several arrangement for testing of telecommuniations switches are known from previous work. For example, U.S. Pat. No. 4,255,625 discloses a call processing monitor system which verifies the operation of a telephone switching center. This particular verification is basically accomplished by the monitor system sending a test tone at a specific frequency only from the terminating side to the originating side of a selected telephone line pair, as is the common practice for the one voice channel path of analog switches. If this transmitted test tone is received by the assigned originating line for the simulated telephone call after traveling through the switching center, it is assumed that a successful call has been made and this indication is duly noted.
Other testing arrangements similar to U.S. Patent No. 4,255,625 are disclosed in the following prior art publications: (a) MASCOT Call Simulator for Digital Switching Systems--ITT Network 2000 (September 1981), and (b) Simulateur d'appels locaux, W. Johner, La Revue Polytechnique No. 1416: pgs. 1319-23 (September 1981). Even though these prior art testing arrangements could conceivably be used on either an analog or a digital switch, the testing technique for each is still limited to the analog switch situation--verifying only the one voice channel path. Thus, for the digital switch situation, its functions are not thoroughly tested by the prior art test sets. Specifically, the prior testing arrangements have failed to consider that in digital switches both the originating to terminating path (O-T) and the terminating to originating path (T-O) should be verified for ensuring the operability of the switch.
Additionally, in the past, none of the switches were examined for noise above a predetermined level in an assigned voice channel path (i.e. terminating to originating lines and originating to terminating lines for a call). With the tremendous recent increase in the reliance upon telephone switching systems for data communications as well as voice, a "quiet test" of this sort would be helpful in determining if the selected telephone line is in compliance with the threshold noise level required for data transmission. Accordingly, this aspect of the operability of the digital or analog switches has not fully tested by the prior art test sets as today's telephony system requires.
With the foregoing in mind, it is a primary object of the present invention to provide an improved testing method and apparatus which is designed to test the important major functions of a digital switch.
More specifically, it is an important object of this invention to provide an improved testing method and apparatus for verifying multiple voice channel paths, and, more particularly, sending a test tone on the terminating and originating lines and detecting its receipt on the rspective originating and terminating lines.
It is a further and more specific object of the present invention to provide a quiet test for the multiple voice channel paths through the telecommunications switch so that noise above a predetermined level can be detected from its terminating to originating lines and also from the originating to terminating lines.